Finn healing increasing on primary and other mods that increase healing/shield

So ever since I saw Helio's Primary mod that stacks shielding on Black Hole I was wondering why other mods of the same caliber didn't do the same. I think now would be the right time to change it. Like for example the increasing heal on Finn's primary can one turn hit 4 people but the next turn it hits 3 and the heal value only goes off the 3 hit. I feel like having the ability to stack would be compliment with other mods currently out there.